In case of a side impact, today's side structures of vehicles permit considerable penetration of parts of the side structure into the interior of the vehicle. The passenger of the vehicle is able to be protected from this by a side airbag. In a usual vehicle, the passenger cell is designed, in addition, in as stable a manner as possible for the side impact. This has the result that only a very limited space is available for dissipating the energy of the side impact.
In order to ensure as great as possible a protection for the passengers in case of a crash, air bags are often used in the related art as frontal air bags, side air bags or head air bags. These air bags, however, function optimally only if the vehicle passenger is located in a predetermined position, and is not removed from this position by the forces occurring during, and directly before the accident. In order to restrain the passenger in this position, a seat belt is frequently used, which is supposed to restrain the vehicle passenger in the appropriate, predetermined position. One should note, however, in this context, that this seat belt, which is mostly designed as a 3-point seat belt, covers a large area of the upper body and thus fixes it, but in the case of a side impact, or in the case of an extreme passenger sitting pose, the effectiveness of the belt is limited. Thus, during an accident, the vehicle passenger may slide sideways from the vehicle seat, for example, or to the front all the way through the seat belt, so that, shortly after an accident, the vehicle passenger is no longer located in the optimal field of effectiveness of the air bag or bags.
In order to prevent such a lateral sliding away, International Patent Publication No. WO 2004/103779 A1 proposes an active seat which is actuated as a function of a sensor system which, for instance, monitors the surroundings of the vehicle. If, for example, an approaching vehicle or a collision of an object with the host vehicle is detected, a lateral support installed in the seat may be set up or advanced reversibly electrically, pneumatically or by a spring-actuated mechanism, so as to position the passenger appropriately.